An Investigation of Moisture Gradient in Wood during Drying Using X-Ray Radiation and Numeric Methods

The moisture gradient in wood is a characteristic of major interest in lumber drying. Two methods, an ovendry slicing method and an X-ray scanning method, were used to examine moisture gradients in wood during the drying of Chinese fir (Cunninghamia lanceolata). The results of the comparison between these two methods confirmed that X-ray radiation can be used to monitor moisture distribution during the drying of Chinese fir. Compared with the moisture content (MC) values obtained by the ovendry slicing method, the X-ray scanning method is capable of determining MC to within ±12.9 percent. Using a control volume approach, a numeric model for estimating the moisture gradient in wood during drying was developed in this work. The validation tests indicated that the model can be used to estimate moisture gradients during the drying of Chinese fir and is capable of predicting moisture distribution to within ±12.6 percent.